1. Field
The present disclosure relates to a light emitting diode (LED) module and a manufacturing method for the LED module, and more particularly, to an LED module having an improved lens connection structure and an increased reliability, and a manufacturing method for the LED module.
2. Description of the Related Art
A light emitting diode (LED) refers to a semiconductor device that emits light when a current flows. Due to a long lifespan, low power consumption, a high response rate, and excellent initial driving characteristics, the LED is widely applied to various fields including a lighting apparatus, an electric sign, and a back light unit of a display device, and the like.
In recent times, the LED is being used as a light source in various colors. With an increase in demands for a high output and high luminance LED, researches have been done actively on increasing performance and reliability of an LED package. To increase performance of an LED product, it is desired to provide not only an LED having a high optical efficiency, but also an LED package efficiently extracting light, and having a high color purity and uniform characteristics of products.
Factors such as color, light velocity and distribution of light intensity may determine characteristics of the LED. The characteristics of the LED may be determined primarily, by compound semiconductor materials used for the LED, and secondarily by a phosphor application method and a package structure.
LED chips, which purport to improve characteristics determined by the primary factors, have been developed rapidly. However, as the development related to the primary factors is currently slowing down, improvement of characteristics determined by the secondary factors is necessary to improve the light velocity and the light intensity distribution. In addition, high reliability of the LED package is in demand.
A phosphor is disposed on a blue LED or an ultraviolet (UV) LED to obtain white light using the LED. A white LED may produce white light by performing a partial color conversion of light extracted from the UV or blue LED through combination of red, green, blue, and yellow phosphors, and then mixing the color-converted light.
The LED may be manufactured in a form of a package or a module to be a product. First, an LED package is prepared by mounting an LED chip on a lead frame and a ceramic substrate, mixing and applying a phosphor according to a desired application, and forming a lens. Next, the LED package is cut into unit LED packages and a unit LED package is mounted on a printed circuit board (PCB), thereby achieving a modularized LED.
The foregoing modularizing structure, in which the LED package is mounted on the PCB, has a limited effect on minimizing of an LED module size. As the mounting is performed two times or more, the inferiority rate may increase, thereby reducing the price of the LED module. In addition, deviations may occur in luminance and color of the LED package due to various factors. The various factors include deviations of luminance and wavelength of the LED, a tolerance in manufacturing a structure such as a lead frame, and a tolerance in processing such as phosphor application and lens formation.
Therefore, to increase uniformity of optical characteristics such as luminance and color of the LED module as a resultant product, LEDs having various luminances and colors are grouped by binning and the respective binned LEDs are combinedly used.
However, when the deviations of luminance and color are great, even by binning of the LEDs, the deviations are not reduced or removed. Therefore, binning groups of the LEDs are determined within a range that does not cause the optical deviation of the LED module. That is, LEDs not included in the determined binning groups are unusable. Accordingly, yield is decreased and the manufacturing cost of producing the LED module is increased.
As a consequence, rather than the package type, a chip-on-board (COB) type module, in which the LED is mounted directly on a module substrate, is manufactured in recent times. The LED module manufactured in the COB type may reduce the manufacturing cost while increasing heat radiation efficiency by shortening a heat transfer path. However, when a lens is provided to the module substrate, the lens may be separated. Hence, there is still room for improvement, for example, in terms of reliability in a lens connection structure of an LED module.